C9148-90909 5 Theory of operation 65
Optical unit
The optical unit consists of the optical unit chassis, the scanning lamp, the CCD driver PCB, and
the optical-unit motor. When the power is turned on, the scanner controller board activates the
optical-unit motor, and the unit begins to move along the rails. When the optical-unit home
sensor flag (located on the bottom of the unit) aligns with the home-position sensor (located on
the scanner controller board; PI1201), the unit stops in the home position.
Figure 25. Optical unit block diagram
The scanner controller board illuminates the flatbed lamp after receiving the scan command from
the copy processor board. As the document is exposed to the illumination of the scanning lamp,
the reflected light from the glass is sent by way of three scanning mirrors and a lens to the CCD
driver PCB for image processing. When the scanning process is complete, the optical unit
returns to the home position.
Figure 26. Scanning process
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